NAIROBI, Kenya — The Somali pirates who hijacked a Ukrainian freighter loaded with tanks, artillery, grenade launchers and ammunition said in an interview on Tuesday that they had no idea the ship was carrying arms when they seized it on the high seas.

“We just saw a big ship,” the pirates’ spokesman, Sugule Ali, said in a telephone interview. “So we stopped it.”

The pirates quickly learned, though, that their booty was an estimated $30 million worth of heavy weaponry, heading for Kenya or Sudan, depending on whom you ask.

In a 45-minute interview, Mr. Sugule spoke on everything from what the pirates wanted (“just money”) to why they were doing this (“to stop illegal fishing and dumping in our waters”) to what they had to eat on board (rice, meat, bread, spaghetti, “you know, normal human-being food”).

He said that so far, in the eyes of the world, the pirates had been misunderstood. “We don’t consider ourselves sea bandits,” he said. “We consider sea bandits those who illegally fish in our seas and dump waste in our seas and carry weapons in our seas. We are simply patrolling our seas. Think of us like a coast guard.”

The pirates who answered the phone call on Tuesday morning said they were speaking by satellite phone from the bridge of the Faina, the Ukrainian cargo ship that was hijacked about 200 miles off the coast of Somalia on Thursday. Several pirates talked but said that only Mr. Sugule was authorized to be quoted. Mr. Sugule acknowledged that they were now surrounded by American warships, but he did not sound afraid. “You only die once,” Mr. Sugule said.

He said that all was peaceful on the ship, despite unconfirmed reports from maritime organizations in Kenya that three pirates were killed in a shootout among themselves on Sunday or Monday night.

He insisted that the pirates were not interested in the weapons and had no plans to sell them to Islamist insurgents battling Somalia’s weak transitional government. “Somalia has suffered from many years of destruction because of all these weapons,” he said. “We don’t want that suffering and chaos to continue. We are not going to offload the weapons. We just want the money.”

He said the pirates were asking for $20 million in cash; “we don’t use any other system than cash.” But he added that they were willing to bargain. “That’s deal-making,” he explained.

Piracy in Somalia is a highly organized, lucrative, ransom-driven business. Just this year, pirates hijacked more than 25 ships, and in many cases, they were paid million-dollar ransoms to release them. The juicy payoffs have attracted gunmen from across Somalia, and the pirates are thought to number in the thousands.

The piracy industry started about 10 to 15 years ago, Somali officials said, as a response to illegal fishing. Somalia’s central government imploded in 1991, casting the country into chaos. With no patrols along the shoreline, Somalia’s tuna-rich waters were soon plundered by commercial fishing fleets from around the world. Somali fishermen armed themselves and turned into vigilantes by confronting illegal fishing boats and demanding that they pay a tax.

“It’s true that the pirates started to defend the fishing business,” Mr. Mohamed said. “And illegal fishing is a real problem for us. But this does not justify these boys to now act like guardians. They are criminals. The world must help us crack down on them.”

The United States and several European countries, in particular France, have been talking about ways to patrol the waters together. The United Nations is even considering something like a maritime peacekeeping force. Because of all the hijackings, the waters off Somalia’s coast are considered the most dangerous shipping lanes in the world.

On Tuesday, several American warships — around five, according to one Western diplomat — had the hijacked freighter cornered along the craggy Somali coastline. The American ships allowed the pirates to bring food and water on board, but not to take weapons off. A Russian frigate is also on its way to the area.

Lt. Nathan Christensen, a Navy spokesman, said on Tuesday that he had heard the unconfirmed reports about the pirate-on-pirate shootout, but that the Navy had no more information. “To be honest, we’re not seeing a whole lot of activity” on the ship, he said.

In Washington, Geoff Morrell, the Pentagon press secretary, declined to discuss any possible American military operations to capture the ship.

“Our concern is right now making sure that there’s a peaceful resolution to this, that this cargo does not end up in the hands of anyone who would use it in a way that would be destabilizing to the region,” Mr. Morrell told reporters at the Pentagon. He said the United States government was not involved in any negotiations with the pirates. He also said he had no information about reports that the pirates had exchanged gunfire among themselves.

Kenyan officials continued to maintain that the weapons aboard were part of a legitimate arms deal for the Kenyan military, even though several Western diplomats, Somali officials and the pirates themselves said the arms were part of a secret deal to funnel weapons to southern Sudan.

Somali officials are urging the Western navies to storm the ship and arrest the pirates because they say that paying ransoms only fuels the problem. Western diplomats, however, have said that such a commando operation would be very difficult because the ship is full of explosives and the pirates could use the 20 crew members as human shields.

Mr. Sugule said his men were treating the crew members well. (The pirates would not let the crew members speak on the phone, saying it was against their rules.) “Killing is not in our plans,” he said. “We only want money so we can protect ourselves from hunger.”